The Blood and the Lymph. 



is thought that these corpuscles are formed in the lymphatic 

 glands. In a disease called scrofula the lymphatic glands 

 become swollen. (See Figs. 49 and 81.) 



- The Flow of Lymph. The flow of lymph is partly due 



to the blood pressure in the capillaries, this pressure is 



caused by the heart. In our bodies the 



flow of lymph is largely aided by any 



pressure on the lymph veins; for, on 



account of the valves, as in the blood 



veins, any pressure must push the liquid 



toward the heart. Thus the action of 



the muscles in the limbs, in the chest, 



in the abdomen, in the movements of 



breathing, and in the bending of the 



body, etc., all help in this flow, which is 



always very much slower than that in 



the blood veins. 



Relations of Blood Flow and Lymph 

 Flow. While the blood leaves the left 

 ventricle by one tube, the aorta, it re- 

 turns to the right auricle, not merely 

 by the two caval veins, but a part of 

 the blood (i.e. of the liquid part of it) 

 does not return by blood veins, but hav- 

 ing left the blood system proper through 

 the thin walls of the capillaries, is 

 brought back by the lymph veins, which, 

 however, join the blood veins just before 

 they empty into the heart. There is 

 only one set of distributing tubes, but 

 there are two sets of collecting or re- 

 turning tubes. 



Fig. 49. Lymphatic 

 Tubes of the Surface 

 of the Arm. Lymph 

 Glands at a, b, c, and d 



